Yasunori Morinaga

Thermally stable exchange-biased magnetic tunnel junctions over 400 °C

Exchange-biased magnetic tunnel junctions (MTJs) with interposed Fe1−xPtx metal alloy layers between the Al oxide barrier and the ferromagnetic electrodes maintain large tunneling magnetoresistance (TMR) after thermal treatment in excess of 400 °C, owing to an improved barrier interface. After 400 °C annealing, TMRs of MTJs with Fe1−xPtx (x=0.1–0.2) exhibit over 40% and retain 30% TMR after 420 °C annealing. The tunnel barrier height derived from the current–voltage curve fitted to the Simmons equation increases with richer Pt content. Secondary ion mass spectroscopy depth profiles and cross-section transmission electron micrographs of MTJs with Fe0.85Pt0.15 show a clear interface around the Al oxide barrier even after annealing at 400 °C.

Highly manufacturable ELK integration technology with metal hard mask process for high performance 32nm-node interconnect and beyond

High performance 32nm-node interconnect with ELK (Extremely Low-k, k=3D2.4) has been demonstrated. To suppress process damage and enlarge the via-line space with a wide lithography process margin, robust ELK film with a metal hard mask (MHM) self-aligned via process has been developed. It has accomplished both ultimate low capacitance wirings and high TDDB reliability between Cu lines with vias. In addition, a novel technique of interface engineering between ELK and a liner layer has been developed to strengthen the tolerance against chip packaging. This has achieved highly reliable chip packaging. This complete process has a high manufacturability and it therefore offers a promising technology for the 32-nm node and beyond.

High-performance metal hard mask process using novel TiN film for 32-nm node Cu interconnect and beyond

One of the most challenging issues in the metal hard mask (MHM) process is controlling the residual stress in TiN mask. This becomes more important as the feature sizes of trenches and vias continue to shrink and the low k-value dielectrics are introduced to Cu interconnect. It is found that the deformation of trenches due to the residual stress in TiN results in Cu voids forming. To overcome this problem, the correlation between the residual stress and the film property of TiN has been investigated. The residual stress in TiN is found to strongly correlate with both the grain size and the crystal structure of TiN, and low residual stress in TiN is accomplished by suppressing the grain growth of TiN. By applying TiN that has a quite fine needle-like structure, the trench deformation can be suppressed and thus the gap filling is perfectly achieved. The MHM process using TiN film that has a needle-like structure is a promising technology for 32-nm node Cu interconnect and beyond.

A novel role for SiCN to suppress H 2 O outgas from TEOS oxide films in hybrid bonding

The novel use of SiCN underneath TEOS oxide as a bonding surface in the wafer bonding of Backside-illuminated (BSI) sensor is proposed and the mechanism of void control by SiCN is clarified. In general, high-temperature processing results in generating voids between the wafer interfaces after bonding due to the release of high-pressure H2O contained in TEOS. In the proposed mechanism, the SiCN exposed to high-temperature H2O is oxidized thereby preventing the emission of high-pressure H2O gas. This paper analyzes the role of SiCN in this mechanism.